1. Field of the Invention
The present invention generally relates to image input apparatuses that correctly determine a sending face (face of a document having information to be sent thereon) or a printing side, and eliminate show-through (bleed-through, images on the back face of a document that show through in the front face), and to image processing apparatuses, image processing methods, image processing programs and storage media storing the image processing programs that perform compression and decompression of image data, and more particularly, to a technique suitable for image processing apparatuses, such as facsimile machines (FAX), scanners, digital copying machines, and printing machines (printers). The present invention may be applied to machines that handle images such as mobile phones, digital cameras, browsers for the Internet, machines for medical use, and machines for satellite communication, and to various application programs, device drivers such as printer drivers, and the like.
2. Description of the Related Art
Conventionally, in facsimile machines, digital copying machines (with ADF), and printers to which papers are manually fed, in many cases, it is difficult to understand whether the sending face or printing side should be up or down. Thus, when using a facsimile apparatus, for example, there is a case where unnecessary trouble and cost occur because the wrong side of an original is sent and the original must be sent again.
Accordingly, in order to eliminate such a problem, there is proposed an image reading apparatus that reads the front face of an original, automatically reverses the original so as to read the back face when the front face is determined to be blank (white), and performs compression and transmission, for example (refer to Japanese Laid-Open Patent Application No. 05-48835).
In addition, there is also an apparatus that reads the front face and the back face with a scanner and determines whether or not the front face or back face is the printing side based on the amount of data of a compressed image (refer to Japanese Laid-Open Patent Application No. 06-245003).
In the image reading apparatus of the former example, however, the side that should not be printed is limited to blank. Thus, when an original is black paper or paper of a brown-colored variety, for example, it is impossible to determine the printing side. Also, with lossy compression by such as the apparatus of the following example, it is difficult to determine the printing side only from the amount of data.
Incidentally, with the progress in image input/output techniques, the demand for higher definition images has increased in recent years. Taking a digital camera as an example of image input apparatuses, price-reduction of high performance charge-coupled devices, having three million or more pixels, advances and such charge-coupled devices are widely used in products of popular price. In addition, regarding technical fields of image output apparatuses and image display apparatuses, achievements in higher-definition and price-reduction in hard copy fields, such as laser printers and ink jet printers, are remarkable. Soft copy fields such as CRTs and LCDs are not exceptions to such phenomena.
The marketing of such high-definition and inexpensive image input/output apparatuses is causing an increase in popularity of high-definition images. In the future, it is expected that the demand for high-definition images will continue to increase in various fields.
Against the background as described above, it is conceived that the demand for compression and decompression techniques capable of easily handling high-definition images will become higher and higher from now on. Thus, conventionally, there is, as one of image compression techniques satisfying the demand, the technique of JPEG 2000 that can process high-definition images by dividing the images into small units and even decode the images of high compression rates with high quality.
As for the type of usage of JPEG 2000, from the characteristics of the data structure, it is conceivable that a server will store compressed images in a network environment, such as the Internet and a server/client system, and the server provides a user or client with all or a part of compressed images in accordance with a request from the user or client.
Considering such type of usage of JPEG 2000 in the network environment, however, it is assumed that the server compresses a large quantity of image data and manages the image data after the compression. In this case, it is anticipated that the server makes mistakes in recognizing the aspects of the images in not just a few cases. Hence, when a user of the Internet or a client in a server/client system accesses image data stored in the server with wrong aspects, of course, there are inconveniences that the aspect of the image output on a display and that of the image output from a printer, for example, are wrong and inappropriate, since the aspects of the image data obtained from the server are also wrong. Such inconveniences are problems to be solved at all cost in terms of difficulty in reading, especially when the image data are based on text images.
It is conceived as the clue for solving the above-described problems to determine whether text images are of vertical writing or horizontal writing. The determination techniques of vertical writing and horizontal writing include techniques described in Japanese Laid-Open Patent Applications No. 05-089284 and No. 08-242336, for example. Japanese Laid-Open Patent Application No. 05-089284 describes the technique of projecting an input image in x-direction and y-direction and performing one-dimensional Fourier transformation for each so as to determine whether the image is of vertical writing or horizontal writing from the size of power spectrum. In addition, Japanese Laid-Open Patent Application No. 08-242336 describes the technique of determining the aspect of an original by using document analysis functions of OCR.
As described above, it is conceived, as the clue for solving the problems of error in determining the aspect of image data, to determine whether text images behind the image data are of vertical writing or horizontal writing. Such determination techniques include the techniques in the above-described applications. In the techniques described in the applications, however, heavy functions (requiring large amounts of computer resources) are required such as one-dimensional Fourier transformation functions and OCR functions so as to determine the aspects of characters and originals. Accordingly, the weight (amounts of computer resource requirements) of such heavy functions becomes a constraint on the practical use of the above-described techniques in a network environment such as the Internet and a server/client system.